use warnings;
use strict;

my $li = "abbjghfg table 1 vinoth figer table2";
my $new_str;
while ( $li =~ m/(.+?)(table.?\d)/gc ) {
    $new_str .= $1 . '<aid=' . $2;
}
print $new_str, $/; #abbjghfg <aid=table 1 vinoth figer <aid=table2